I swapped the radiator on my 01 ls430.
Its pretty easy and this is the cliff notes from what I recall (swapped it feb '13, haven't had any issues and swapped it in 2.5 hours )
i would recommend having some long needle nose pliers for the clips, and a philips screwdriver.
1) Remove the top air duct
2) Drain out the fluid
3) Pull out the plumbing (Don't forget the transmission lines, they are best reached from underneath the car with under car shield removed)
4) Remove top 2 clasps for radiator, on the bottom there may be 2 screws as well. (Manual mentioned 2, but my car only had 2 screws on top holding the radiator)
5) Remove the fans (complete assembly comes off after 4-5 screws)
6) Use some insulation around the radiators edge (picked up from home depot)
7) re-install, re-connect coolant/transmission lines to radiator. Connect the fans, fill up the radiator and reservoir and check for leaks.
As a heads up, if you go with a "replacement" unit, (i purchased one from 1-800 radiator for ~$170 | See thread: http://www.clublexus.com/forums/ls43...-question.html
There are 2 options for radiators, one has the thicker core ment for ls430's with a towing package (koyo #: A2419 ) . The thicker core was plug-and-play. I have had no issues since Feb '13. The temperature sits at the lower tick (instead of dead center of the gauge).